Night vision is of critical importance for anyone who needs to see unaided at night. For example, a person at the helm of a boat at night needs to be able to pick out navigational aids on the water and still read the compass and other instruments in front of him.
Halogen lamps provide broad band spectral radiation ranging from the ultraviolet through the visible and into the infrared. This broad band of radiation is similar to that emitted by the sun, and is the most comfortable lighting to read with. However, the presence of this broad band of radiation will cause a person's pupils to narrow, rendering a person on a boat at night unable to clearly see things not illuminated by the halogen lamp. For night vision, red light-emitting diodes (LEDs), which typically have narrow bands of spectral radiation around 620 nm, are ideal. This is because the human eye is least sensitive to red light, and the pupil will remain wide open in response to red light, allowing the eye to remain acclimated to the night and see outside the area illuminated by the red light.